(1) Field of the Invention
The present invention relates to fluorine-containing compounds having phosphonitrile amides as substituents. These are synthetic lubricants having a solid or pasty consistency at normal temperatures and obtained by introducing different types of fluorine-containing compounds as well as synthetic lubricants which are liquids at normal temperatures and obtained by introducing identical or different types of fluorine-containing compounds.
The lubricants in accordance with the invention may take the form of solid and liquid lubricants and are capable of being used for the lubrication and corrosion protection of the contact surfaces of machinery or equipment with moving parts, in which applications they will provide a superior effect.
(2) Description of the Prior Art
Polychlorophosphonitrile, a compound consisting of chlorine, phosphorus, and nitrogen atoms, can be obtained in high yield by reacting phosphorus pentachloride with ammonium chloride, and from these, organic phosphonitriles are obtained by bonding them with organic compounds having a straight chain or an aromatic ring structure, such organic phosphonitriles being used as flame retardants, synthetic rubbers, and synthetic lubricants.
Organic straight-chained polymeric phosphonitriles that are used as synthetic rubbers and trimeric, tetrameric and oligomeric phosphonitriles with organic ring structures in the molecule are known from U.S. Pat. Nos. 2,109,490, 3,131,207, 4,018,967, and 4,613,548 and have also been described in the literature in the A.S.L.E. Transactions 7, 389-397 (1964), and applications thereof have been described in the Japanese Patent Provisional Publication Nos. 252292/1986, 260088/1986, and 250098/1987.
These are given as being compounds obtained by reacting trimeric and tetrameric polychlorophosphonitriles with alkoxy-substituted phosphonitriles and an alkyl or aryl amine.
Many types of lubricants for electronic equipment used in recent years, for example, surface lubricants for magnetic recording devices as well as lubricants for connectors and contactors, employ a variety of inorganic and organic substances, and their use has demonstrated that it is difficult to extend the surface life of the equipment solely by virtue of the lubricants' wetting power.
Moreover, perfluoroalkyl polyethers are being used as oil and grease lubricants for bearings. Their problem, however, is that due to the lack of adhesion onto the metal surface they lead to an inferior corrosion resistance and to a reduced service life of the bearing, so that means are being sought to resolve these difficulties.
Fluorinated lubricants are being widely used in applications requiring a chemical inertness and heat resistance, and research and development has been directed toward the achievement of stable compounds rather than compounds resistant to extremely severe application conditions.
The principal application fields are therefore limited to the semiconductor industry using non-combustible corrosive gases with a low vapor pressure, for bearings, plant conveyors and chains as well as furnace peripherals liable to operate at elevated temperatures.
The superior qualities of fluorinated lubricants, however, can be recognized from the fact that these compounds are being applied to a wide range of applications in factory automation, industrial robots, computer equipment, and electric household appliances.
These lubricants have to meet a broad range of requirements when used in such equipment, and experience so far has shown that fluorinated lubricants are in many instances not capable of fulfilling these requirements.
Perfluorinated alkylpolyether lubricants, that is, compounds in which all hydrogen atoms have been replaced by fluorine, do not posses satisfactory load carrying capacity in the low-molecular range but exhibit a satisfactory wettability and a low surface tension in the high-molecular range. Yet, due to their poor adhesion to metals, their use would give rise to lubricant migration and loss of lubrication performance if and when used for the lubrication of equipment rotating at high speed.
If the compounds are rendered too stable, it will thus be found that the adsorption on to metals will be weakened and that though exhibiting a satisfactory lubricating effect in the initial period, their effectiveness as lubricants for sliding away equipment tends to diminish, if used for a prolonged period of time, due to lubricant depletion consequent to lubricant migration.
For this reason, it is essential to enhance lubricant adsorption and improve the wear resistance of lubricants even if this implies a certain trade-off by sacrificing their stability to a certain extent, as may be required by some applications.